Pacquiao Mosley- The variable of age

One more week to go before these future Hall of Famers meet up. One of the biggest variables being talked about in relation to this fight is the age factor.
Mosley is 39 years old. A grandfather to some in the sports of boxing. However, he has proven that he can still go the distance (his last two fights went the full 12) and has exhibited flashes of his old self when he ran over the much bigger Margarito. The question remain however, if he still has enough fuel in his tank to withstand the onslaught of the 32 year old pound for pound champion?